cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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ns16550.c (2137B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * 16550 serial console support.
      4 *
      5 * Original copied from <file:arch/ppc/boot/common/ns16550.c>
      6 * (which had no copyright)
      7 * Modifications: 2006 (c) MontaVista Software, Inc.
      8 *
      9 * Modified by: Mark A. Greer <mgreer@mvista.com>
     10 */
     11#include <stdarg.h>
     12#include <stddef.h>
     13#include "types.h"
     14#include "string.h"
     15#include "stdio.h"
     16#include "io.h"
     17#include "ops.h"
     18#include "of.h"
     19
     20#define UART_DLL	0	/* Out: Divisor Latch Low */
     21#define UART_DLM	1	/* Out: Divisor Latch High */
     22#define UART_FCR	2	/* Out: FIFO Control Register */
     23#define UART_LCR	3	/* Out: Line Control Register */
     24#define UART_MCR	4	/* Out: Modem Control Register */
     25#define UART_LSR	5	/* In:  Line Status Register */
     26#define UART_LSR_THRE	0x20	/* Transmit-hold-register empty */
     27#define UART_LSR_DR	0x01	/* Receiver data ready */
     28#define UART_MSR	6	/* In:  Modem Status Register */
     29#define UART_SCR	7	/* I/O: Scratch Register */
     30
     31static unsigned char *reg_base;
     32static u32 reg_shift;
     33
     34static int ns16550_open(void)
     35{
     36	out_8(reg_base + (UART_FCR << reg_shift), 0x06);
     37	return 0;
     38}
     39
     40static void ns16550_putc(unsigned char c)
     41{
     42	while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
     43	out_8(reg_base, c);
     44}
     45
     46static unsigned char ns16550_getc(void)
     47{
     48	while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
     49	return in_8(reg_base);
     50}
     51
     52static u8 ns16550_tstc(void)
     53{
     54	return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
     55}
     56
     57int ns16550_console_init(void *devp, struct serial_console_data *scdp)
     58{
     59	int n;
     60	u32 reg_offset;
     61
     62	if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1) {
     63		printf("virt reg parse fail...\r\n");
     64		return -1;
     65	}
     66
     67	n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
     68	if (n == sizeof(reg_offset))
     69		reg_base += be32_to_cpu(reg_offset);
     70
     71	n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
     72	if (n != sizeof(reg_shift))
     73		reg_shift = 0;
     74	else
     75		reg_shift = be32_to_cpu(reg_shift);
     76
     77	scdp->open = ns16550_open;
     78	scdp->putc = ns16550_putc;
     79	scdp->getc = ns16550_getc;
     80	scdp->tstc = ns16550_tstc;
     81	scdp->close = NULL;
     82
     83	return 0;
     84}